Introducing superconductivity into a topological insulator (TI) while preserving its nontrivial band topology provides a promising and widely explored route for realizing topological superconductivity and Majorana zero modes. Here, we report pressure-induced superconductivity in Bi2Se3 nanoflakes and bulk crystals while the system remains in the topologically nontrivial R“3” ̅m phase. Under quasi-hydrostatic conditions, superconducting transitions emerge at 2.4 GPa with Daphne 7373 and are independently reproduced at 2.5 GPa using argon as the pressure-transmitting medium. In contrast, under non-hydrostatic conditions, superconductivity appears only after a structural transition from the R“3” ̅m phase to the monoclinic (C2/m) phase. Hall measurements and first-principles calculations further reveal pronounced pressure-induced changes in carrier density, electronic structure, and lattice dynamics. These results identify pressure uniformity as a key factor enabling superconductivity to emerge while preserving the topological R“3” ̅m phase of Bi2Se3.